1. Field of the Invention
The present invention relates to the reduction of a sulfonic acid to its corresponding thiol.
2. Description of the Prior Art
Sulfonic acids, e.g., such aryl sulfonic acids as benzenesulfonic acid, are described as being directly reducible to the corresponding thiols by use of a trifluoroacetic anhydride-tetrabutylammonium iodide mixture by T. Numata et al. in Tetrahedron Letters, Vol. 21, 1235-1238 (1980). This route is indicated as being the "first example" of the direct reduction of such sulfonic acids to the corresponding thiol. Numata et al. do indicate, however, that various sulfonic acid derivatives (e.g., the sulfonyl halide, sulfonamide, and sulfonate derivatives) are reducible with more typical reducing agents.